Anxiety Disorders are Associated with Reduced Heart Rate Variability: A Meta-Analysis

Diagnosis of major depressive disorder by combining multimodal information from heart rate dynamics and serum proteomics using machine-learning algorithm

OBJECTIVE

Major depressive disorder (MDD) is a systemic and multifactorial disorder that involves abnormalities in multiple biochemical pathways and the autonomic nervous system. This study applied a machine-learning method to classify MDD and control groups by incorporating data from serum proteomic analysis and heart rate variability (HRV) analysis for the identification of novel peripheral biomarkers.

METHODS

The study subjects consisted of 25 drug-free female MDD patients and 25 age- and sex-matched healthy controls. First, quantitative serum proteome profiles were analyzed by liquid chromatography-tandem mass spectrometry using pooled serum samples from 10 patients and 10 controls. Next, candidate proteins were quantified with multiple reaction monitoring (MRM) in 50 subjects. We also analyzed 22 linear and nonlinear HRV parameters in 50 subjects. Finally, we identified a combined biomarker panel consisting of proteins and HRV indexes using a support vector machine with recursive feature elimination.

RESULTS

A separation between MDD and control groups was achieved using five parameters (apolipoprotein B, group-specific component, ceruloplasmin, RMSSD, and SampEn) at 80.1% classification accuracy. A combination of HRV and proteomic data achieved better classification accuracy.

CONCLUSIONS

A high classification accuracy can be achieved by combining multimodal information from heart rate dynamics and serum proteomics in MDD. Our approach can be helpful for accurate clinical diagnosis of MDD. Further studies using larger, independent cohorts are needed to verify the role of these candidate biomarkers for MDD diagnosis.

Resting state vagal tone in attention deficit (hyperactivity) disorder: A meta-analysis

OBJECTIVES

To quantify evidence on resting-state vagal activity in patients with attention deficit hyperactivity disorder (ADHD) relative to controls using meta-analysis.

METHODS

Three electronic databases (PubMed, PsycINFO, CINAHL Plus) were reviewed to identify studies. Studies reporting on any measure of short-term, vagally mediated heart rate variability during resting state in clinically diagnosed ADHD patients as well as non-ADHD healthy controls were eligible for inclusion.

RESULTS

Eight studies reporting on 587 participants met inclusion criteria. Random-effect meta-analysis revealed no significant main effect comparing individuals with ADHD (n = 317) and healthy controls (n = 270) (Hedges' g = 0.06, 95% CI: 0.18-0.29, Z = 0.48, P = 0.63; k = 8). Sub-group analysis showed consistent results among studies in adults (k = 2) and children (k = 6) with ADHD.

CONCLUSIONS

Unlike a variety of internalising psychiatric disorders, ADHD is not associated with altered short-term measures of resting-state vagal tone.

Trauma and Autonomic Dysregulation: Episodic-Versus Systemic-Negative Affect Underlying Cardiovascular Risk in Posttraumatic Stress Disorder

OBJECTIVE

Posttraumatic stress disorder (PTSD) has been linked to elevated heart rate (HR) and reduced heart rate variability (HRV) in cross-sectional research. Recent evidence suggests that this link may be driven by individual differences in autonomic arousal associated with momentary negative affect (NA). Using ecological momentary assessment (EMA) of NA and minute-to-minute HR/HRV monitoring, we examined whether NA-related HR/HRV mediated the association of PTSD symptom severity with 24-hour HRV and endothelial functioning.

METHODS

One hundred ninety-seven young adults (18-39 years), 93 with PTSD, underwent 1 day of Holter monitoring while concurrently reporting NA levels via EMA. Two noninvasive measures of endothelial functioning-flow-mediated dilation and hyperemic flow-were also collected. Multilevel modeling was used to assess the associations of momentary NA with HR and low- and high-frequency HRV during the 5-minute intervals after each EMA reading. Latent variable modeling was then used to determine whether individual differences in these associations mediated the association of PTSD symptom severity with 24-hour HRV, flow-mediated dilation, and hyperemic flow.

RESULTS

PTSD symptom severity was positively associated with NA-related autonomic arousal (β = .21, p < .001), which significantly mediated the association of PTSD symptom severity with 24-hour HRV and hyperemic flow, accounting for 62% and 34% of their associations, respectively, while overshadowing the influence of smoking, lifetime alcohol dependence, sleep duration, mean NA, and episodes of acute NA.

CONCLUSIONS

Results suggest that NA-related autonomic arousal is both a primary factor driving cardiovascular risk in PTSD and a potential point of intervention.

Character strengths, social anxiety, and physiological stress reactivity

In this paper, the effects of character strengths on the physiological reactivity to social anxiety induced by the Trier Social Stress Task were reported. On the basis of their scores in the Chinese Virtues Questionnaire, 30 college students were assigned to either high- (n = 15) or low-character-strength (n = 15) groups. Their psychological stress and physiological data across three laboratory stages (namely, baseline, stress exposure, and post-stress) were collected. Results indicated that individuals with high character strengths exhibited rapid cardiovascular recovery from baseline to post-stress even if high- and low-character-strength groups showed similar patterns of cardiovascular arousal in response to the stress at baseline and stress exposure. These results prove that character strengths are stress-defense factors that allow for psychological and physiological adaptation to stress.

Attention-deficit/hyperactivity disorder symptoms and stress-related biomarkers

OBJECTIVE

The current study examined whether (a) Attention-Deficit/Hyperactivity Disorder (ADHD) symptoms were associated with dysregulation of stress-related mechanisms, and (b) whether ADHD symptoms interact with affective disorders in their association with dysregulated stress-related mechanisms.

METHODS

Data were obtained from 2307 subjects participating in the Netherlands Study of Depression and Anxiety. Stress-related mechanisms were reflected by the following biomarkers: (1) hypothalamic-pituitary-adrenal axis indicators (salivary cortisol awakening curve, evening cortisol, cortisol suppression after a 0.5mg dexamethasone suppression test (DST)); (2) autonomic nervous system measures (heart rate, pre-ejection period, respiratory sinus arrhythmia); (3) inflammatory markers (C-reactive protein, interleukin-6, tumor necrosis factor-alpha); (4) brain-derived neurotrophic factor. ADHD symptoms were measured using Conners' Adult ADHD Rating Scale and used both dichotomous (High ADHD symptoms (yes/no)) and continuous (Inattentive symptoms, Hyperactive/Impulsive symptoms, and the ADHD index).

RESULTS

Regression analyses showed associations between High ADHD symptoms, Inattentive symptoms, the ADHD index and a higher cortisol awakening curve, between Hyperactive/Impulsive symptoms and less cortisol suppression after DST, and between Inattentive symptoms and a longer pre-ejection period. However, the associations with the cortisol awakening curve disappeared after adjustment for depressive and anxiety disorders. No associations were observed between ADHD symptoms and inflammatory markers or BDNF. ADHD symptoms did not interact with affective disorders in dysregulation of stress-related mechanisms.

CONCLUSION

Some associations were observed between ADHD symptoms, the HPA-axis, and the pre-ejection period, but these were mostly driven by depressive and anxiety disorders. This study found no evidence that ADHD symptomatology was associated with dysregulations in inflammatory markers and BDNF. Consequently, ADHD symptoms did not confer an added risk to the disturbances of stress-related mechanisms in an - already at-risk - population with affective disorders.

Biological markers for anxiety disorders, OCD and PTSD: A consensus statement. Part II: Neurochemistry, neurophysiology and neurocognition

OBJECTIVE

Biomarkers are defined as anatomical, biochemical or physiological traits that are specific to certain disorders or syndromes. The objective of this paper is to summarise the current knowledge of biomarkers for anxiety disorders, obsessive-compulsive disorder (OCD) and posttraumatic stress disorder (PTSD).

METHODS

Findings in biomarker research were reviewed by a task force of international experts in the field, consisting of members of the World Federation of Societies for Biological Psychiatry Task Force on Biological Markers and of the European College of Neuropsychopharmacology Anxiety Disorders Research Network.

RESULTS

The present article (Part II) summarises findings on potential biomarkers in neurochemistry (neurotransmitters such as serotonin, norepinephrine, dopamine or GABA, neuropeptides such as cholecystokinin, neurokinins, atrial natriuretic peptide, or oxytocin, the HPA axis, neurotrophic factors such as NGF and BDNF, immunology and CO2 hypersensitivity), neurophysiology (EEG, heart rate variability) and neurocognition. The accompanying paper (Part I) focuses on neuroimaging and genetics.

CONCLUSIONS

Although at present, none of the putative biomarkers is sufficient and specific as a diagnostic tool, an abundance of high quality research has accumulated that should improve our understanding of the neurobiological causes of anxiety disorders, OCD and PTSD.

Non-invasive vagus nerve stimulation reduces sympathetic preponderance in patients with tinnitus

CONCLUSION

Transcutaneous vagal nerve stimulation (tVNS) might offer a targeted, patient-friendly, and low-cost therapeutic tool for tinnitus patients with sympathovagal imbalance.

OBJECTIVES

Conventionally, VNS has been performed to treat severe epilepsy and depression with an electrode implanted to the cervical trunk of vagus nerve. This study investigated the acute effects of tVNS on autonomic nervous system (ANS) imbalance, which often occurs in patients with tinnitus-triggered stress.

METHODS

This study retrospectively analysed records of 97 patients who had undergone ANS function testing by heart rate variability (HRV) measurement immediately before and after a 15-60 min tVNS stimulation.

RESULTS

The pre-treatment HRV recording showed sympathetic preponderance/reduced parasympathetic activity in about three quarters (73%) of patients. Active tVNS significantly increased variability of R-R intervals in 75% of patients and HRV age was decreased in 70% of patients. Either the variability of R-R intervals was increased or the HRV age decreased in 90% of the patients. These results indicate that tVNS can induce a shift in ANS function from sympathetic preponderance towards parasympathetic predominance. tVNS caused no major morbidity, and heart rate monitoring during the tVNS treatment showed no cardiac or circulatory effects (e.g. bradycardia) in any of the patients.

The Association between Self-Reported Difficulties in Emotion Regulation and Heart Rate Variability: The Salient Role of Not Accepting Negative Emotions

Difficulties in emotion regulation are associated with development and maintenance of psychopathology. Typically, features of emotion regulation are assessed with self-report questionnaires. Heart rate variability (HRV) is an objective measure proposed as an index of emotional regulation capacity. A limited number of studies have shown that self-reported difficulties in emotion regulation are associated with HRV. However, results from prior studies are inconclusive, and an ecological validation of the association has not yet been tested. Therefore, further exploration of the relation between self-report questionnaires and psychophysiological measures of emotional regulation is needed. The present study investigated the contribution of self-reported emotion regulation difficulties on HRV in a student sample. We expected higher scores on emotion regulation difficulties to be associated with lower vagus-mediated HRV (vmHRV). Sixty-three participants filled out the Difficulties in Emotion Regulation Scale and their resting HRV was assessed. In addition, a subsample of participants provided ambulatory 24-h HRV data, in order to ecologically validate the resting data. Correlation analyses indicated that self-reported difficulties in emotion regulation was negatively associated with vmHRV in both resting HRV and 24-h HRV. Specifically, when exploring the contribution of the different facets of emotion dysregulation, the inability to accept negative emotions showed the strongest association with HRV. The results are discussed and need for future research is described.

Higher locus coeruleus MRI contrast is associated with lower parasympathetic influence over heart rate variability

The locus coeruleus (LC) is a key node of the sympathetic nervous system and suppresses parasympathetic activity that would otherwise increase heart rate variability. In the current study, we examined whether LC-MRI contrast reflecting neuromelanin accumulation in the LC was associated with high-frequency heart rate variability (HF-HRV), a measure reflecting parasympathetic influences on the heart. Recent evidence indicates that neuromelanin, a byproduct of catecholamine metabolism, accumulates in the LC through young and mid adulthood, suggesting that LC-MRI contrast may be a useful biomarker of individual differences in habitual LC activation. We found that, across younger and older adults, greater LC-MRI contrast was negatively associated with HF-HRV during fear conditioning and spatial detection tasks. This correlation was not accounted for by individual differences in age or anxiety. These findings indicate that individual differences in LC structure relate to key cardiovascular parameters.

Diurnal Variation and Twenty-Four Hour Sleep Deprivation Do Not Alter Supine Heart Rate Variability in Healthy Male Young Adults

Heart rate variability (HRV) has become an increasingly popular index of cardiac autonomic control in the biobehavioral sciences due to its relationship with mental illness and cognitive traits. However, the intraindividual stability of HRV in response to sleep and diurnal disturbances, which are commonly reported in mental illness, and its relationship with executive function are not well understood. Here, in 40 healthy adult males we calculated high frequency HRV—an index of parasympathetic nervous system (PNS) activity—using pulse oximetry during brain imaging, and assessed attentional and executive function performance in a subsequent behavioral test session at three time points: morning, evening, and the following morning. Twenty participants were randomly selected for total sleep deprivation whereas the other 20 participants slept as normal. Sleep deprivation and morning-to-night variation did not influence high frequency HRV at either a group or individual level; however, sleep deprivation abolished the relationship between orienting attention performance and HRV. We conclude that a day of wake and a night of laboratory-induced sleep deprivation do not alter supine high frequency HRV in young healthy male adults.

Major depressive disorder and generalized anxiety disorder show different autonomic dysregulations revealed by heart-rate variability analysis in first-onset drug-naïve patients without comorbidity

AIM

The aim of the present study was to examine whether depression and anxiety disorder manifest different autonomic dysregulations using heart-rate variability (HRV) and heart rate (HR) measurements.

METHODS

HRV and HR were recorded both at rest and during task execution (random-number generation) in first-onset drug-naïve patients with major depressive disorder (MDD, n = 14) and generalized anxiety disorder (GAD, n = 11) as well as in healthy controls (n = 41). The patients showed no comorbidity of depression and anxiety disorder. GAD patients did not exhibit panic or phobic symptoms at the time of measurement. Following power spectrum analysis of HR trend, the high- (HF) and low-frequency (LF) components, the sum (LF + HF), and the LF/HF ratio were compared among the groups.

RESULTS

In the MDD patients, as previously reported, HF was low and the LF/HF ratio was high during the initial-rest condition, and HF was less reactive to the task. In contrast, GAD patients showed significantly high HF, although autonomic reactivity was not impaired.

CONCLUSION

The results indicate that baseline autonomic activity and its reactivity to behavioral changes are different between MDD and GAD in the early stage of illness. High parasympathetic tone in GAD may reflect responses of the parasympathetic system to anxiety. MDD is accompanied by an autonomic shift toward sympathetic activation and a reduced reactivity to task.

Inflammation in Fear- and Anxiety-Based Disorders: PTSD, GAD, and Beyond

The study of inflammation in fear- and anxiety-based disorders has gained interest as growing literature indicates that pro-inflammatory markers can directly modulate affective behavior. Indeed, heightened concentrations of inflammatory signals, including cytokines and C-reactive protein, have been described in posttraumatic stress disorder (PTSD), generalized anxiety disorder (GAD), panic disorder (PD), and phobias (agoraphobia, social phobia, etc.). However, not all reports indicate a positive association between inflammation and fear- and anxiety-based symptoms, suggesting that other factors are important in future assessments of inflammation's role in the maintenance of these disorders (ie, sex, co-morbid conditions, types of trauma exposure, and behavioral sources of inflammation). The most parsimonious explanation of increased inflammation in PTSD, GAD, PD, and phobias is via the activation of the stress response and central and peripheral immune cells to release cytokines. Dysregulation of the stress axis in the face of increased sympathetic tone and decreased parasympathetic activity characteristic of anxiety disorders could further augment inflammation and contribute to increased symptoms by having direct effects on brain regions critical for the regulation of fear and anxiety (such as the prefrontal cortex, insula, amygdala, and hippocampus). Taken together, the available data suggest that targeting inflammation may serve as a potential therapeutic target for treating these fear- and anxiety-based disorders in the future. However, the field must continue to characterize the specific role pro-inflammatory signaling in the maintenance of these unique psychiatric conditions.

Is the link between depressed mood and heart rate variability explained by disinhibited eating and diet?

Consistently it has been reported that a depressed mood and low heart rate variability (HRV) are linked. However, studies have not considered that the association might be explained by dietary behaviour. The resting inter-beat interval data of 266 adults (Study 1: 156 (51M), Study 2: 112 (38M)) were recorded for six minutes and quantified using linear (HF power: 0.15-0.4Hz) and nonlinear indices (Sample entropy). Participants also completed the Profile of Mood States and the Three Factor Eating questionnaires. The Alternative Healthy Eating Index was used to quantify diet quality. In study 1 mood was associated with HRV; an effect partially mediated by diet. Study 2 replicated the finding: disinhibited eating (the tendency to lose control over one's eating) and diet sequentially mediated the association between mood and HRV. Diet plays a role in the link between mood and HRV and studies should consider the influence of this factor.

Statistical considerations for reporting and planning heart rate variability case-control studies

The calculation of heart rate variability (HRV) is a popular tool used to investigate differences in cardiac autonomic control between population samples. When interpreting effect sizes to quantify the magnitude of group differences, researchers typically use Cohen's guidelines of small (0.2), medium (0.5), and large (0.8) effects. However, these guidelines were originally proposed as a fallback for when the effect size distribution (ESD) was unknown. Despite the availability of effect sizes from hundreds of HRV studies, researchers still largely rely on Cohen's guidelines to interpret effect sizes and to perform power analyses to calculate required sample sizes for future research. This article describes an ESD analysis of 297 HRV effect sizes from between-group/case-control studies, revealing that the 25th, 50th, and 75th effect size percentiles correspond with effect sizes of 0.26, 0.51, and 0.88, respectively. The analyses suggest that Cohen's guidelines may underestimate the magnitude of small and large effect sizes and that HRV studies are generally underpowered. Therefore, to better reflect the observed ESD, effect sizes of 0.25, 0.5, and 0.9 should be interpreted as small, medium, and large effects (after rounding to the closest 0.05). Based on power calculations using the ESD, suggested sample sizes are also provided for planning suitably powered studies that are more likely to replicate. Researchers are encouraged to use the ESD data set or their own collected data sets in tandem with the provided analysis script to perform custom ESD and power analyses relevant to their specific research area.

Heart rate variability: Pre-deployment predictor of post-deployment PTSD symptoms

Heart rate variability is a physiological measure associated with autonomic nervous system activity. This study hypothesized that lower pre-deployment HRV would be associated with higher post-deployment post-traumatic stress disorder (PTSD) symptoms. Three-hundred-forty-three Army National Guard soldiers enrolled in the Warriors Achieving Resilience (WAR) study were analyzed. The primary outcome was PTSD symptom severity using the PTSD Checklist - Military version (PCL) measured at baseline, 3- and 12-month post-deployment. Heart rate variability predictor variables included: high frequency power (HF) and standard deviation of the normal cardiac inter-beat interval (SDNN). Generalized linear mixed models revealed that the pre-deployment PCL*ln(HF) interaction term was significant (p<0.0001). Pre-deployment SDNN was not a significant predictor of post-deployment PCL. Covariates included age, pre-deployment PCL, race/ethnicity, marital status, tobacco use, childhood abuse, pre-deployment traumatic brain injury, and previous combat zone deployment. Pre-deployment heart rate variability predicts post-deployment PTSD symptoms in the context of higher pre-deployment PCL scores.

Resting-state high-frequency heart rate variability is related to respiratory frequency in individuals with severe mental illness but not healthy controls

Heart rate variability (HRV) has become central to biobehavioral models of self-regulation and interpersonal interaction. While research on healthy populations suggests changes in respiratory frequency do not affect short-term HRV, thus negating the need to include respiratory frequency as a HRV covariate, the nature of the relationship between these two variables in psychiatric illness is poorly understood. Therefore, the aim of this study was to investigate the association between HRV and respiratory frequency in a sample of individuals with severe psychiatric illness (n = 55) and a healthy control comparison group (n = 149). While there was no significant correlation between HF-HRV and respiration in the control group, we observed a significant negative correlation in the psychiatric illness group, with a 94.1% probability that these two relationships are different. Thus, we provide preliminary evidence suggesting that HF-HRV is related to respiratory frequency in severe mental illness, but not in healthy controls, suggesting that HRV research in this population may need to account for respiratory frequency. Future work is required to better understand the complex relationship between respiration and HRV in other clinical samples with psychiatric diseases.

Heart rate variability and generalized anxiety disorder during laboratory-induced worry and aversive imagery

BACKGROUND

To date only a few published studies have examined the effect of disorder-relevant stressors on heart rate variability (HRV) in participants meeting a clinical diagnosis of GAD, with conflicting results. The primary aim of this study was to determine if GAD is associated with lower HRV at rest, and whether vagal regulation during task varies by type (i.e., baseline, anticipation, imagery, or worry).

METHODS

This study investigated resting cardiac vagal tone and vagal regulation in a sample of 40 participants with or without a validated diagnosis of generalized anxiety disorder (GAD). High-frequency heart rate variability (HF-HRV) was used to index cardiac vagal activity.

RESULTS

GAD was associated with vagal withdrawal during both imagery and worry inductions, but no group differences in resting vagal tone or worry were observed.

LIMITATIONS

Methodological limitations include inherent limits to generalizability of laboratory-based findings; specifically worry induction and cardiac reactivity to lab-based stressors.

CONCLUSIONS

The results support the notion that GAD is associated with vagal withdrawal during active bouts of idiographic worry and imagery, and question the assumption that GAD is associated with low resting vagal tone. In light of polyvagal theory these findings provide additional support for the presence of emotion regulation deficits in GAD, and identify specific ANS processes that underlie GAD.

[Changes and differences of heart rate variability of patients in a psychiatric rehabilitation clinic]

BACKGROUND

A reduced heart rate variability (HRV) has been associated with various different pathological physical and psychological conditions and illnesses. The present study is focused on investigating HRV in respect to psychological disorders (depressive disorders anxiety disorders, Burn-out-Syndrome).

METHODS

The results from an investigation with patients from a psychiatric Rehabilitation clinic following a six week in-patient treatment are presented.

RESULTS

The results show relevant changes in HRV in the course of the rehabilitative treatment for patients with depressive disorders, anxiety disorders or Burn-out-Syndrome. Simultaneously changes in HRV were linked with improvements in patient's psychological symptoms. Changes in HRV (i. e. an increase of relevant HRV-parameters) were accompanied by a reduction of psychological strain as well as psychological and physical health problems, which typically occur in Burnout-Syndrome. Furthermore, changes in relevant HRV-parameters were predictive of changes in psychological symptoms (depression, anxiety, phobia, Burnout symptoms).

CONCLUSIONS

The present study did show, that in respect to the investigation of the relationship between HRV and subjective data, primarily those HRV-parameters are important (in terms of significant results) which are based on parasympathetic activity. These results are interesting in the context of theories, which view vagal mediated HRV as positively connected with self-regulation, adaptability and positive interpersonal interaction of individuals.

Altered functional connectivity of interoception in illness anxiety disorder

Interoception collects all information coming from the body and is sustained by several brain areas such as insula and cingulate cortex. Here, we used resting-state functional magnetic resonance imaging to investigate functional connectivity (FC) of networks implied in interoception in patients with Illness anxiety disorders (IADs). We observed significantly reduced FC between the left extrastriate body area (EBA) and the paracentral lobule compared to healthy controls. Moreover, the correlation analysis between behavioural questionnaires and ROI to ROI FC showed that higher levels of illness anxiety were related to hyper-connectivity between EBA and amygdala and hippocampus. Scores on a questionnaire for interoceptive awareness were significantly correlated with higher FC between right hippocampus and nucleus accumbens bilaterally, and with higher connectivity between left anterior cingulate cortex (ACC) and left orbitofrontal cortex (OFC). Last, patients showed increased interoceptive awareness, measured by Self-Awareness Questionnaire (SAQ), and reduced capability in recognizing emotions, indicating inverse correlation between interoception and emotional awareness. Taken together our results suggested that, in absence of structural and micro-structural changes, patients with IADs show functional alteration in the neural network involved in the self-body representation; such functional alteration might be the target of possible treatments.

Health anxiety and risk of ischaemic heart disease: a prospective cohort study linking the Hordaland Health Study (HUSK) with the Cardiovascular Diseases in Norway (CVDNOR) project

BACKGROUND

The risk of ischaemic heart disease (IHD) is largely influenced by lifestyle. Interestingly, cohort studies show that anxiety in general is associated with increased risk of IHD, independent of established risk factors for cardiovascular disease. Health anxiety is a specific type of anxiety characterised by preoccupation of having, acquiring or possibly avoiding illness, yet little is known about lifestyle and risk of disease development in this group.

AIM

Investigate whether health anxiety is prospectively associated with IHD, and whether a potential association can be explained by the presence or absence of established risk factors for cardiovascular diseases.

METHODS

Incident IHD was studied among 7052 participants in the community-based Hordaland Health Study (HUSK) during 12 years follow-up by linkage to the Cardiovascular Diseases in Norway (CVDNOR) project. Scores above 90th centile of the Whiteley Index defined health anxiety cases. Associations were examined with the Cox proportional regression models.

RESULTS

During follow-up, 6.1% of health anxiety cases developed IHD compared with 3.0% of non-cases, yielding a gender-adjusted HR of 2.12 (95% CI 1.52 to 2.95). After adjustments for established cardiovascular risk factors, about 70% increased risk of IHD was found among cases with health anxiety (HR: 1.73 (95% CI 1.21 to 2.48)). The association followed a dose-response pattern.

CONCLUSIONS

This finding corroborates and extends the understanding of anxiety in various forms as a risk factor for IHD. New evidence of negative consequences over time underlines the importance of proper diagnosis and treatment for health anxiety.

Correlation between health-related quality of life in the physical domain and heart rate variability in asymptomatic adults

Background

Reduced health-related quality of life in the physical domain (HRQOL_physical) has been reported to increase risks for cardiovascular disease (CVD); however, the mechanism underlying this phenomenon is still unclear. The autonomic nervous system (ANS) that connects the body and mind is a biologically plausible candidate to investigate this mechanism. The aim of our study is to examine whether the HRQOL_physical independently contributes to heart rate variability (HRV), which reflects ANS activity.

Methods

We recruited 329 physically and mentally healthy adults. All participants completed Beck Anxiety Inventory, Beck Depression Inventory and World Health Organization Questionnaire on Quality of Life: Short Form-Taiwanese version (WHOQOL-BREF). They were divided into groups of individuals having high or low scores of HRQOL_physical as discriminated by the quartile value of WHOQOL-BREF. We obtained the time and frequency-domain indices of HRV, namely variance (total HRV), the low-frequency power (LF; 0.05–0.15 Hz), which may reflect baroreflex function, the high-frequency power (HF; 0.15–0.40 Hz), which reflects cardiac parasympathetic activity, and the LF/HF ratio.

Results

There was an independent contribution of HRQOL_physical to explaining the variance in HRV after excluding potential confounding factors (gender, age, physical activity, alcohol use, depression and anxiety). Compared with the participants with high levels of HRQOL_physical, those with low levels of HRQOL_physical displayed significant reductions in variance and LF.

Conclusions

This study highlights the independent role of low HRQOL_physical in contributing to the reduced HRV in healthy adults and points to a potential underlying mechanism for HRQOL_physical to confer increased risks for CVD.

Atypical reactivity of heart rate variability to stress and depression across development: Systematic review of the literature and directions for future research

Heart rate variability has received growing attention in the depression literature, with several recent meta-analyses indicating that lower resting heart rate variability is associated with depression. However, the role of fluctuations in heart rate variability (or reactivity) in response to stress in depression remains less clear. The present review provides a systematic examination of the literature on heart rate variability reactivity to a laboratory-induced stressor task and depression, including 26 studies of reactivity in heart rate variability and clinical depression, remitted (or history of) depression, and subthreshold depression (or symptom-level depression) among adults, adolescents, and children. In addition to reviewing the findings of these studies, methodological considerations and conceptual gaps in the literature are addressed. We conclude by highlighting the importance of investigating the potential transactional relationship between heart rate variability reactivity and depression and possible mechanisms underlying this relationship.

Desynchronization of autonomic response and central autonomic network connectivity in posttraumatic stress disorder

OBJECTIVES

Although dysfunctional emotion regulatory capacities are increasingly recognized as contributing to posttraumatic stress disorder (PTSD), little work has sought to identify biological markers of this vulnerability. Heart rate variability (HRV) is a promising biomarker that, together with neuroimaging, may assist in gaining a deeper understanding of emotion dysregulation in PTSD. The objective of the present study was, therefore, to characterize autonomic response patterns, and their related neuronal patterns in individuals with PTSD at rest.

METHODS

PTSD patients (N = 57) and healthy controls (N = 41) underwent resting-state fMRI. Connectivity patterns of key regions within the central autonomic network (CAN)-including the ventromedial prefrontal cortex (vmPFC), amygdala, and periaqueductal gray (PAG)-were examined using a seed-based approach. Observed connectivity patterns were then correlated to resting HRV.

RESULTS

In contrast to controls, individuals with PTSD exhibited lower HRV. In addition, whereas controls engaged a localized connectivity pattern of CAN-related brain regions, in PTSD, key CAN regions were associated with widespread connectivity patterns in regions related to emotional reactivity (vmPFC and amygdala to insular cortex and lentiform nucleus; PAG to insula) and motor readiness (vmPFC and amygdala to precentral gyrus; PAG to precentral gyrus and cerebellum). Critically, whereas CAN connectivity in controls was strongly related to higher HRV (insula, mPFC, superior frontal cortex, thalamus), HRV covariation was absent in PTSD subjects.

CONCLUSIONS

This study provides the first evidence for a specific psychophysiological-neuronal profile in PTSD individuals characterized by lower resting HRV and a lack of HRV covariation with CAN-related brain connectivity. Hum Brain Mapp 38:27-40, 2017. © 2016 Wiley Periodicals, Inc.

Examining the Crux of Autonomic Dysfunction in Posttraumatic Stress Disorder: Whether Chronic or Situational Distress Underlies Elevated Heart Rate and Attenuated Heart Rate Variability

OBJECTIVE

Posttraumatic stress disorder (PTSD) has been linked to elevated heart rate (HR) and reduced heart rate variability (HRV) in cross-sectional research. Using ecological momentary assessment and minute-to-minute HRV/HR monitoring, we examined whether cross-sectional associations between PTSD symptom severity and HRV/HR were due to overall elevations in distress levels or to attenuated autonomic regulation during episodes of acute distress.

METHODS

Two hundred nineteen young adults (18-39 years old), 99 with PTSD, underwent 1 day of Holter monitoring and concurrently reported distress levels via ecological momentary assessment. Using multilevel modeling, we examined the associations between momentary distress and the 5-minute means for low-frequency (LF) and high-frequency (HF) HRV and HR immediately following distress ratings, and whether PTSD symptom severity moderated these associations.

RESULTS

Compared with the controls, participants with PTSD recorded higher ambulatory distress (mean [standard deviation] = 1.7 [0.5] versus 1.2 [0.3], p < .001) and HR (87.2 [11.8] versus 82.9 [12.6] beats/min, p = .011), and lower ambulatory LF HRV (36.9 [14.7] versus 43.7 [16.9 ms, p = .002) and HF HRV (22.6 [12.3] versus 26.4 [14.6] milliseconds, p = .043). Overall distress level was not predictive of HR or HRV (p values > .27). However, baseline PTSD symptom severity was associated with elevated HR (t(1257) = 2.76, p = .006) and attenuated LF (t(1257) = -3.86, p < .001) and HF (t(1257) = -2.62, p = .009) in response to acute momentary distress.

CONCLUSIONS

Results suggest that PTSD is associated with heightened arousal after situational distress and could explain prior findings associating PTSD with HR/HRV. Implications for treatment and cardiovascular risk are discussed.

Psychoneuroimmunological aspects of cardiovascular diseases: a preliminary report

Aim of the study

Due to their prevalence and negative social effects, cardiovascular diseases belong to a group of civilization diseases. Previous research suggests comorbidity of heart diseases, mood disorders and impaired cognitive functioning. The aim of this study was to evaluate the psychoneuroimmunological aspects of functioning in patients diagnosed with cardiovascular diseases.

Material and methods

Ten persons, mean age 48.2 years old, diagnosed with primary hypertension, were studied. All of them were treated with beta blockers and ACE inhibitors with unsuccessful therapeutic effect. This group also included 4 subjects with heart rate disturbances. The control group included 10 clinically healthy volunteers in mean age 46.8. All participants had 24-hour ECG monitoring with Holter method in order to evaluate the autonomic activity with time and frequency domain analysis (heart rate variability). Patients also underwent neuropsychological assessment of quality of life and personality traits (EQ-5D, NEO-PI-R, PSS10, SWLS, MHLC). Quantitative evaluation of immune system parameters included: TCD3, TCD4, CD8, CD16/CD56, CD19, HLA-DR+.

Results

The cardiovascular disease group showed significantly lower time and frequency domain parameters (p < 0.05) except low/high frequency (LF/HF) power ratio. The heart rhythm disorder group demonstrated significant relationships such as: Quality of life with Total Power of HRV and day-time LF/HF ratio, pNN50 and rMSSD – negative correlation.

Conclusions

1. In cardiovascular disease patients, activity of the autonomic nervous system is significantly reduced. 2. Impaired modulation of the autonomic nervous system activity affects mood and decreases quality of life. 3. In patients with heart rhythm disturbances, increased sympathetic nervous system activity affects prolonged tension and the immune response.

Reduced heart rate variability in remitted bipolar disorder and recurrent depression

OBJECTIVE

There is evidence that mood disorders are associated with impaired parasympathetic nervous system function and consequently increased morbidity and mortality. Our study addresses whether this impairment persists into remission in unipolar and bipolar disorders.

METHODS

Heart Rate Variability was measured in groups of subjects during remission, with Bipolar Affective Disorder I (n = 29), recurrent Major Depressive Disorder (n = 41) and a healthy control group (n = 38), during the bedtime period.

RESULTS

Heart Rate Variability was found to be lower in the bipolar and depression groups, compared with control subjects, using the Root Mean Square of Successive Distances variable, and lower in the depression group using the Standard Deviation of Normal to Normal variable and the Standard Deviation, Poincare Plot variable.

CONCLUSION

Autonomic function during bedtime was impaired in subjects with Bipolar I and recurrent Major Depressive Disorder, despite clinical remission. This has significant implications for the morbidity and mortality of patients with major mood disorders.

Association of depression and psychotropic medication on cardiac-related outcomes in a nationwide community-dwelling elderly population in Taiwan

The objective of this study was to examine the association of depression, psychotropic medications, and mental illness with cardiovascular disease in a nationwide community-dwelling elderly population in Taiwan. A total of 5664 participants who enrolled in the Healthy Aging Longitudinal Study in Taiwan (HALST) were included in the study. Multiple logistic regression was applied to investigate the association of depression, psychotropic medication use, and mental illness, separately, with cardiovascular disease. The results suggested that cardiovascular disease was significantly associated with various definitions of depression, including: the Center for Epidemiologic Studies-Depression scale (CES-D) ≥ 16, self-reported, and physician-diagnosed for depression (adjusted odds ratio [AOR] = 1.51; 95% confidence interval (CI): 1.14-2.00 for CES-D; AOR = 3.29; 95% CI: 1.99-5.42 for self-reported; and AOR = 2.45; 95% CI: 1.51-3.97 for physician-diagnosed). Additionally, significant associations of cardiovascular disease with the use of antipsychotics (AOR = 2.04; 95% CI: 1.25-3.34), benzodiazepines (BZDs) (AOR = 1.84; 95% CI: 1.52-2.21), and Z-drugs (AOR = 1.41; 95% CI: 1.03-1.93), respectively, were also observed, but not the use of antidepressants. In addition, a significant association of cardiovascular disease with mental illness was found in this study (AOR = 2.33; 95% CI: 1.68-3.24). In line with previous reports, these findings provided supportive evidence that depression and/or mental illness were significantly associated with cardiovascular disease in a community-dwelling elderly population in Taiwan. Moreover, significant associations of cardiovascular disease with the use of antipsychotics, BZDs, and Z-drugs, individually, were found. Further investigation would be of importance to clarify the causal relationship of depression and/or psychotropic medications with cardiovascular disease, especially among elderly populations.

Amygdala functional connectivity as a longitudinal biomarker of symptom changes in generalized anxiety

Generalized anxiety disorder (GAD) is characterized by excessive worry, autonomic dysregulation and functional amygdala dysconnectivity, yet these illness markers have rarely been considered together, nor their interrelationship tested longitudinally. We hypothesized that an individual’s capacity for emotion regulation predicts longer-term changes in amygdala functional connectivity, supporting the modification of GAD core symptoms. Sixteen patients with GAD (14 women) and individually matched controls were studied at two time points separated by 1 year. Resting-state fMRI data and concurrent measurement of vagally mediated heart rate variability were obtained before and after the induction of perseverative cognition. A greater rise in levels of worry following the induction predicted a stronger reduction in connectivity between right amygdala and ventromedial prefrontal cortex, and enhanced coupling between left amygdala and ventral tegmental area at follow-up. Similarly, amplified physiological responses to the induction predicted increased connectivity between right amygdala and thalamus. Longitudinal shifts in a distinct set of functional connectivity scores were associated with concomitant changes in GAD symptomatology over the course of the year. Results highlight the prognostic value of indices of emotional dysregulation and emphasize the integral role of the amygdala as a critical hub in functional neural circuitry underlying the progression of GAD symptomatology.

Impaired resting vagal tone in patients with functional movement disorders

INTRODUCTION

The autonomic nervous system plays an integral role in the maintenance of homeostasis during times of stress. The functioning of the autonomic nervous system in patients with functional movement disorders (FMD) is of particular interest given the hypothesis that converted psychological stress plays a critical role in FMD disease pathogenesis. We sought to investigate autonomic nervous system activity in FMD patients by examining heart rate variability (HRV), a quantitative marker of autonomic function.

METHODS

35 clinically definite FMD patients and 38 age- and sex-matched healthy controls were hospitalized overnight for continuous electrocardiogram recording. Standard time and frequency domain measures of HRV were calculated in the awake and asleep stages. All participants underwent a thorough neuropsychological battery, including the Hamilton Anxiety and Depression scales and the Beck Depression Inventory.

RESULTS

Compared to controls, patients with FMD exhibited decreased root mean square of successive differences between adjacent NN intervals (RMSSD) (p = 0.02), a marker of parasympathetic activity, as well as increased mean heart rate (p = 0.03). These measures did not correlate with the depression and anxiety scores included in our assessment as potential covariates.

CONCLUSION

In this exploratory study, patients with FMD showed evidence of impaired resting state vagal tone, as demonstrated by reduced RMSSD. This decreased vagal tone may reflect increased stress vulnerability in patients with FMD.

Worry is associated with robust reductions in heart rate variability: a transdiagnostic study of anxiety psychopathology

BACKGROUND

Individuals with anxiety disorders display reduced resting-state heart rate variability (HRV), although findings have been contradictory and the role of specific symptoms has been less clear. It is possible that HRV reductions may transcend diagnostic categories, consistent with dimensional-trait models of psychopathology. Here we investigated whether anxiety disorders or symptoms of anxiety, stress, worry and depression are more strongly associated with resting-state HRV.

METHODS

Resting-state HRV was calculated in participants with clinical anxiety (n = 25) and healthy controls (n = 58). Symptom severity measures of worry, anxiety, stress, and depression were also collected from participants, regardless of diagnosis.

RESULTS

Participants who fulfilled DSM-IV criteria for an anxiety disorder displayed diminished HRV, a difference at trend level significance (p = .1, Hedges' g = -.37, BF10 = .84). High worriers (Total n = 41; n = 22 diagnosed with an anxiety disorder and n = 19 not meeting criteria for any psychopathology) displayed a robust reduction in resting state HRV relative to low worriers (p = .001, Hedges' g = -.75, BF10 = 28.16).

CONCLUSIONS

The specific symptom of worry - not the diagnosis of an anxiety disorder - was associated with the most robust reductions in HRV, indicating that HRV may provide a transdiagnostic biomarker of worry. These results enhance understanding of the relationship between the cardiac autonomic nervous system and anxiety psychopathology, providing support for dimensional-trait models consistent with the Research Domain Criteria framework.

Trait Self-Compassion Reflects Emotional Flexibility Through an Association with High Vagally Mediated Heart Rate Variability

Converging evidence shows a positive effect of self-compassion on self-reported well-being and mental health. However, few studies have examined the relation between self-compassion and psychophysiological measures. In the present study, we therefore examined the relation between trait self-compassion and vagally mediated heart rate variability (vmHRV) in 53 students (39 female, mean age = 23.63). Trait self-compassion was assessed using the Self-Compassion Scale, and resting vmHRV was measured during a 5-min ECG baseline period. We hypothesized that higher levels of trait self-compassion would predict higher levels of resting vmHRV. Controlling for potential covariates (including age, gender, and BMI), the results confirmed our hypotheses, showing that higher levels of trait self-compassion predicted higher vmHRV. These results were validated with a 24-h measure of vmHRV, acquired from a subsample of the participants (n = 26, 16 female, mean age = 23.85), confirming the positive correlation between high trait self-compassion and higher vmHRV. The relation between trait self-compassion, vmHRV, self-reported trait anxiety (the trait scale of the State-Trait Anxiety Inventory; STAI) and self-reported rumination (the Rumination subscale of the Rumination-Reflection Questionnaire; RRQ-Rum) was also investigated. Higher levels of trait anxiety and rumination were highly correlated with low levels of trait self-compassion. Trait anxiety, but not rumination, correlated marginally significantly with the level of vmHRV. The findings of the present study indicate that trait self-compassion predicts a better ability to physiologically and psychologically adapt emotional responses. Possible implications and limitations of the study are discussed.

A Meta-analysis on Resting State High-frequency Heart Rate Variability in Bulimia Nervosa

OBJECTIVE

Autonomic nervous system function is altered in eating disorders. We aimed to quantify differences in resting state vagal activity, indexed by high-frequency heart rate variability comparing patients with bulimia nervosa (BN) and healthy controls.

METHODS

A systematic search of the literature to identify studies eligible for inclusion and meta-analytical methods were applied. Meta-regression was used to identify potential covariates.

RESULTS

Eight studies reporting measures of resting high-frequency heart rate variability in individuals with BN (n = 137) and controls (n = 190) were included. Random-effects meta-analysis revealed a sizeable main effect (Z = 2.22, p = .03; Hedge's g = 0.52, 95% CI [0.06;0.98]) indicating higher resting state vagal activity in individuals with BN. Meta-regression showed that body mass index and medication intake are significant covariates.

DISCUSSION

Findings suggest higher vagal activity in BN at rest, particularly in unmedicated samples with lower body mass index. Potential mechanisms underlying these findings and implications for routine clinical care are discussed. Copyright © 2016 John Wiley & Sons, Ltd and Eating Disorders Association.

Heart rate variability is associated with amygdala functional connectivity with MPFC across younger and older adults

The ability to regulate emotion is crucial to promote well-being. Evidence suggests that the medial prefrontal cortex (mPFC) and adjacent anterior cingulate (ACC) modulate amygdala activity during emotion regulation. Yet less is known about whether the amygdala-mPFC circuit is linked with regulation of the autonomic nervous system and whether the relationship differs across the adult lifespan. The current study tested the hypothesis that heart rate variability (HRV) reflects the strength of mPFC-amygdala interaction across younger and older adults. We recorded participants' heart rates at baseline and examined whether baseline HRV was associated with amygdala-mPFC functional connectivity during rest. We found that higher HRV was associated with stronger functional connectivity between the amygdala and the mPFC during rest across younger and older adults. In addition to this age-invariant pattern, there was an age-related change, such that greater HRV was linked with stronger functional connectivity between amygdala and ventrolateral PFC (vlPFC) in younger than in older adults. These results are in line with past evidence that vlPFC is involved in emotion regulation especially in younger adults. Taken together, our results support the neurovisceral integration model and suggest that higher heart rate variability is associated with neural mechanisms that support successful emotional regulation across the adult lifespan.

Heartbeat scaling in early adolescents: Its association with anxiety symptoms and sensitivity to punishment

Background/Objective: Anxiety symptoms in adolescence have been found to be associated with heart rate variability (HRV) linear features, but more basic properties of the cardiac system remain unexplored. This study focused on the fractal nature of 90 minute-long interbeat fluctuations from 24 adolescents with high anxiety and 26 with low anxiety to (a) evaluate if allometric scaling exponents and linear HRV measures allow for distinction between groups, and (b) assess the associations between these measures and sensitivity to punishment (SP), a temperamental characteristic strongly correlated with anxiety. Method: Cardiac functioning was recorded and allometric exponents and vagally mediated HRV as indexed by the high frequency (HF) band power were calculated. Results: While the exponents from the high anxiety group were significantly higher than those from low anxiety participants (p < .05), just marginal differences were found for the HF measure (p = .057). Furthermore, exponents were positively correlated with SP scores and several anxiety scale scores, but no more correlations were found. Conclusions: These results show that beyond parasympathetic functioning, basic properties of the cardiac system may be altered in young, anxious adolescents. These properties, therefore, can provide useful information for assessing adolescents at risk of anxiety disorders.

Heart rate variability and the relationship between trauma exposure age, and psychopathology in a post-conflict setting

BACKGROUND

Cumulative exposure to potentially traumatic events (PTEs) increases risk for mental distress in conflict-affected settings, but the psychophysiological mechanisms that mediate this dose-response relationship are unknown. We investigated diminished heart rate variability (HRV) - an index of vagus nerve function and a robust predictor of emotion regulation capacity - as a vulnerability marker that potentially mediates the association between PTE exposure, age and symptoms of posttraumatic stress disorder (PTSD), psychological distress and aggressive behavior, in a community sample from Timor-Leste - a post-conflict country with a history of mass violence.

METHOD

Resting state heart rate data was recorded from 45 cases of PTSD, depression and intermittent explosive disorder (IED); and 29 non-case controls.

RESULTS

Resting HRV was significantly reduced in the combined case group compared with non-cases (p = .021; Cohen's d = 0.5). A significant mediation effect was also observed, whereby a sequence of increased age, reduced HRV and elevated PTSD symptoms mediated the association between PTE exposure and distress (B = .06, SE = .05, 95% CI = [.00-.217]) and aggression (B = .02, SE = .02, 95% CI = [.0003-.069])).

CONCLUSION

The findings demonstrate an association between diminished resting HRV and psychopathology. Moreover, age-related HRV reductions emerged as a potential psychophysiological mechanism that underlies enhanced vulnerability to distress and aggression following cumulative PTE exposure.

Guidelines for Reporting Articles on Psychiatry and Heart rate variability (GRAPH): recommendations to advance research communication

The number of publications investigating heart rate variability (HRV) in psychiatry and the behavioral sciences has increased markedly in the last decade. In addition to the significant debates surrounding ideal methods to collect and interpret measures of HRV, standardized reporting of methodology in this field is lacking. Commonly cited recommendations were designed well before recent calls to improve research communication and reproducibility across disciplines. In an effort to standardize reporting, we propose the Guidelines for Reporting Articles on Psychiatry and Heart rate variability (GRAPH), a checklist with four domains: participant selection, interbeat interval collection, data preparation and HRV calculation. This paper provides an overview of these four domains and why their standardized reporting is necessary to suitably evaluate HRV research in psychiatry and related disciplines. Adherence to these communication guidelines will help expedite the translation of HRV research into a potential psychiatric biomarker by improving interpretation, reproducibility and future meta-analyses.

Effect of emotion regulation training in patients with panic disorder: Evidenced by heart rate variability measures

OBJECTIVE

We aimed to examine the effect of emotion regulation training in patients with panic disorder (PD) by measuring heart rate variability (HRV).

METHODS

Forty-eight patients with PD were randomly divided into emotion regulation group (n=25) and no-regulation group (n=23). Three five-minute ECG recordings were taken in the following states: 1) baseline, 2) while subjects viewed 15 aversive pictures (active stimulus), 3) resting state after aversive pictures (post-stimulus). The emotion regulation group briefly received acceptance technique training for five minutes before performing the experimental task. Spectral analysis measures included a high-frequency (HF; 0.15-0.4 HZ) component, a low-frequency (LF; 0.04-0.15Hz) component, and an LF/HF ratio.

RESULTS

The mean change in LF/HF ratio from baseline to active stimulus was significantly lower in the emotion regulation group than in the no-regulation group (emotion regulation group, 0.13; no-regulation group, 2.31; t=-2.67; P<.05).

CONCLUSION

This suggests that brief emotion acceptance training could decrease aversive stimulus-induced sympathetic hyperactivity in patients with PD.

Genetic influences on heart rate variability

Heart rate variability (HRV) is the variation of cardiac inter-beat intervals over time resulting largely from the interplay between the sympathetic and parasympathetic branches of the autonomic nervous system. Individual differences in HRV are associated with emotion regulation, personality, psychopathology, cardiovascular health, and mortality. Previous studies have shown significant heritability of HRV measures. Here we extend genetic research on HRV by investigating sex differences in genetic underpinnings of HRV, the degree of genetic overlap among different measurement domains of HRV, and phenotypic and genetic relationships between HRV and the resting heart rate (HR). We performed electrocardiogram (ECG) recordings in a large population-representative sample of young adult twins (n=1060 individuals) and computed HRV measures from three domains: time, frequency, and nonlinear dynamics. Genetic and environmental influences on HRV measures were estimated using linear structural equation modeling of twin data. The results showed that variability of HRV and HR measures can be accounted for by additive genetic and non-shared environmental influences (AE model), with no evidence for significant shared environmental effects. Heritability estimates ranged from 47 to 64%, with little difference across HRV measurement domains. Genetic influences did not differ between genders for most variables except the square root of the mean squared differences between successive R-R intervals (RMSSD, higher heritability in males) and the ratio of low to high frequency power (LF/HF, distinct genetic factors operating in males and females). The results indicate high phenotypic and especially genetic correlations between HRV measures from different domains, suggesting that >90% of genetic influences are shared across measures. Finally, about 40% of genetic variance in HRV was shared with HR. In conclusion, both HR and HRV measures are highly heritable traits in the general population of young adults, with high degree of genetic overlap across different measurement domains.

Dominant hemisphere lateralization of cortical parasympathetic control as revealed by frontotemporal dementia

The brain continuously influences and perceives the physiological condition of the body. Related cortical representations have been proposed to shape emotional experience and guide behavior. Although previous studies have identified brain regions recruited during autonomic processing, neurological lesion studies have yet to delineate the regions critical for maintaining autonomic outflow. Even greater controversy surrounds hemispheric lateralization along the parasympathetic-sympathetic axis. The behavioral variant of frontotemporal dementia (bvFTD), featuring progressive and often asymmetric degeneration that includes the frontoinsular and cingulate cortices, provides a unique lesion model for elucidating brain structures that control autonomic tone. Here, we show that bvFTD is associated with reduced baseline cardiac vagal tone and that this reduction correlates with left-lateralized functional and structural frontoinsular and cingulate cortex deficits and with reduced agreeableness. Our results suggest that networked brain regions in the dominant hemisphere are critical for maintaining an adaptive level of baseline parasympathetic outflow.

Is there cardiac risk in panic disorder? An updated systematic review

BACKGROUND

The recognized relationship between panic disorder (PD) and cardiac disorders (CDs) is not unequivocal. We reviewed the association between PD and coronary artery disease (CAD), arrhythmias, cardiomyopathies, and sudden cardiac death.

METHODS

We undertook an updated systematic review, according to PRISMA guidelines. Relevant studies dating from January 1, 2000, to December 31, 2014, were identified using the PubMed database and a review of bibliographies. The psychiatric and cardiac diagnostic methodology used in each study was then to very selective inclusion criteria.

RESULTS

Of 3044 studies, 14 on CAD, 2 on cardiomyopathies, and 1 on arrhythmias were included. Overall, the studies supported a panic-CAD association. Furthermore, in some of the studies finding no association between current full-blown PD and CAD, a broader susceptibility to panic, manifesting as past PD, current agoraphobia, or subthreshold panic symptoms, appeared to be relevant to the development of CAD. Preliminary data indicated associations between panic, arrhythmias, and cardiomyopathies.

LIMITATIONS

The studies were largely cross-sectional and conducted in cardiological settings. Only a few included blind settings. The clinical conditions of patients with CDs and the qualifications of raters of psychiatric diagnoses were highly heterogeneous. CDs other than CAD had been insufficiently investigated.

CONCLUSIONS

Our review supported a relationship between PD and CDs. Given the available findings and the involvement of the cardiorespiratory system in the pathophysiology of PD, an in-depth investigation into the panic-CDs association is highly recommended. This should contribute to improved treatment and prevention of cardiac events and/or mortality, linked to PD.

Mechanistic Pathways of Mindfulness Meditation in Combat Veterans With Posttraumatic Stress Disorder

OBJECTIVE

This study's objective was to evaluate the effect of two common components of meditation (mindfulness and slow breathing) on potential mechanistic pathways.

METHODS

A total of 102 combat veterans with posttraumatic stress disorder (PTSD) were randomized to (a) the body scan mindfulness meditation (MM), (b) slow breathing (SB) with a biofeedback device, (c) mindful awareness of the breath with an intention to slow the breath (MM+SB), or (d) sitting quietly (SQ). Participants had 6 weekly one-on-one sessions with 20 minutes of daily home practice. The mechanistic pathways and measures were as follows: (a) autonomic nervous system (hyperarousal symptoms, heart rate [HR], and heart rate variability [HRV]); (b) frontal cortex activity (attentional network task [ANT] conflict effect and event-related negativity and intrusive thoughts); and (c) hypothalamic-pituitary-adrenal axis (awakening cortisol). PTSD measures were also evaluated.

RESULTS

Meditation participants had significant but modest within-group improvement in PTSD and related symptoms, although there were no effects between groups. Perceived impression of PTSD symptom improvement was greater in the meditation arms compared with controls. Resting respiration decreased in the meditation arms compared with SQ. For the mechanistic pathways, (a) subjective hyperarousal symptoms improved within-group (but not between groups) for MM, MM+SB, and SQ, while HR and HRV did not; (b) intrusive thoughts decreased in MM compared with MM+SB and SB, while the ANT measures did not change; and (c) MM had lower awakening cortisol within-group (but not between groups).

CONCLUSION

Treatment effects were mostly specific to self-report rather than physiological measures. Continued research is needed to further evaluate mindfulness meditation's mechanism in people with PTSD.

Hippotherapy acute impact on heart rate variability non-linear dynamics in neurological disorders

Neurological disorders are associated with autonomic dysfunction. Hippotherapy (HT) is a therapy treatment strategy that utilizes a horse in an interdisciplinary approach for the physical and mental rehabilitation of people with physical, mental and/or psychological disabilities. However, no studies have been carried out which evaluated the effects of HT on the autonomic control in these patients. Therefore, the objective of the present study was to investigate the effects of a single HT session on cardiovascular autonomic control by time domain and non-linear analysis of heart rate variability (HRV). The HRV signal was recorded continuously in twelve children affected by neurological disorders during a HT session, consisting in a 10-minute sitting position rest (P1), a 15-minute preparatory phase sitting on the horse (P2), a 15-minute HT session (P3) and a final 10-minute sitting position recovery (P4). Time domain and non-linear HRV indices, including Sample Entropy (SampEn), Lempel-Ziv Complexity (LZC) and Detrended Fluctuation Analysis (DFA), were calculated for each treatment phase. We observed that SampEn increased during P3 (SampEn=0.56±0.10) with respect to P1 (SampEn=0.40±0.14, p<0.05), while DFA decreased during P3 (DFA=1.10±0.10) with respect to P1 (DFA=1.26±0.14, p<0.05). A significant SDRR increase (p<0.05) was observed during the recovery period P4 (SDRR=50±30ms) with respect to the HT session period P3 (SDRR=30±10ms). Our results suggest that HT might benefit children with disabilities attributable to neurological disorders by eliciting an acute autonomic response during the therapy and during the recovery period.